Bilirubin is a yellow substance which is formed in the blood as a result of degradation of hemoglobin, and is the principal pigment of bile manufactured in the liver. It has been estimated that approximately 200-230 milligrams of bilirubin and its derivatives are formed each day in a healthy human adult by the degradation of hemoglobin within the liver, spleen and bone marrow.
The diagnostic significance of bilirubin is well established. For example, an excessive amount of bilirubin within the human body, referred to as jaundice, is recognized as evidence of a variety of disease conditions, particularly diseases of the liver. In addition, jaundice often occurs in new born infants whose liver is slow to begin normal function. Thus, to facilitate early diagnosis of certain disease states and/or to actively reduce bilirubin levels, a bilirubin specific enzyme would be very useful.
Enzymes shown to be specific for bilirubin have been partially purified and characterized from fungi, as described in U.S. Pat. No. 4,211,844 (issued July 8, 1980 to Wu). However, the enzymes obtained from such sources, particularly from the mushrooms described in U.S. Pat. No. 4,211,844, noted above, have relatively modest specificity towards bilirubin. When used in crude form, the enzyme preparation has relatively low specific activity, thereby necessitating larger quantities of enzymes for providing acceptable assay results.
Hence, it would be desirable to have a highly active enzyme preparation specific to degrading bilirubin and suitable for improved bilirubin assays.